This invention is an improvement of the liquid rocket engine of the type that utilizes liquid propellant, which may be a cryogenic propellant (liquid hydrogen and liquid oxygen) or other liquid propellants which are typically used for rocket engines. And more particularly, this invention constitutes an improvement over the class of engines identified as the RL10 rocket engines and other types of liquid rocket engines manufactured by Pratt & Whitney a division of United Technologies Corporation, the assignee common to the assignee of this patent application.
As is well known in this field of technology, the RL10 family of liquid rocket engines utilize a plurality of tubes that are joined together to conform to the contour of the thrust chamber which consists of a combustion chamber and a nozzle. Each tube extends from the entrance of the combustion chamber to the discharge end of the nozzle. The tubes are parallely disposed relative to each other and are joined such as by welding or brazing to form the thrust chamber assembly. The diameter of the tubes may vary. The extremely cold liquid hydrogen from the hydrogen pump(s) is pumped through these tubes which flows in indirect heat exchange with the combustion products in the combustion chamber and nozzle. The heated liquid hydrogen becomes sufficiently heated to form a gas which is then utilized to power the power turbine in the rocket's turbopumps. After the energy is extracted from the heated hydrogen the, now, cooler hydrogen is then fed to the injector to combine with the liquid oxygen to combust in the thrust chamber and hence, develop thrust. The thrust chamber of the other liquid rocket engines that utilize liquid propellants that may not be cryogenic are also similarly constructed.
As is well known in this field of technology, there are continuing demands on these rocket engines for producing higher and higher thrust. While the regenerative cooling system as described above has been adequate for certain rocket engine models, the requirement for additional thrust which occasions higher heat loads in the thrust chamber has put increasingly higher demands on the structural integrity on the construction of these tubes and particularly on the braze of those components that are brazed and are subject to these high heat loads.
We have found that we can obviate the problems incidental to the higher temperature problems associated with the assembly and bond of these tubes providing a hook at each end of each tube that is attached to each of a pair of manifolds mounted at the top and bottom ends of the thrust chamber. The hooks are bent and configured such that the upper end of each of the tubes lie in a generally horizontal direction relative to the engine's axis and the lower end of each of the tubes lie in a generally vertical direction relative to the rocket engines center line and in fact, lie generally parallel to the rocket engine's center line. The open end of the bottom tubes face the hooks at the upper end of the tubes such that the hook is bent in a direction away from the rocket engine's nozzle and substantially greater than ninety (90) degrees and is somewhat U-shaped. This serves a dual purpose. First, it isolates the brazed ends of the cooling tubes from the heat source of the combustion products in the rocket engine's combustion chamber and nozzle. Second, this construction enhances the method of assembly of the cooling tubes to the manifolds that are typically employed with the tubes. The vertical portion of the bottom end of the tubes permit the manifold which may be a full hoop or segmented and joined near the throat section of the thrust chamber and then lowered vertically onto each of the vertical ends of the tubes after the horizontal ends have been assembled into the upper manifold. A wedge ring supporting the bottom manifold is lowered along the thrust chamber and ultimately engages and bears against the outer periphery of the tubes so as to provide a precise fit between the manifold and the outer diameter of the tubes that are configured into the tubular shaped thrust chamber. This construction is such that the logistics of the brazed portions places the brazed ends of the tubes away from the high temperature portion of the thrust chamber and in a relatively cold environment which enhances the strength and or durability of the thrust chamber and nozzle which inherently enhances the fatigue life of the component parts.
The location of the manifold of this construction lends itself to provide means for defining a base to support the rocket engine for storage purposes. This invention contemplates forming integrally with or attaching to the bottom manifold a skirt that has a horizontal planar bottom surface that forms a base to support the engine in an upright position for storage or installation purposes.